Cal. Wat. Code § 46380
If the amount of the interim project assessment or assessments credited with respect to any tract of land pursuant to Section 46379 exceeds the amount of the original assessment to finance the project with respect to said tract, said excess shall be credited against said interim project assessment or assessments, which, to that extent, shall cease to be a lien with respect to said tract. If the amount theretofore collected by the district on the interim project assessment or assessments with respect to any tract of land exceeds the amount of the original assessment with respect to said tract, such excess shall be a claim against and debt of the district, and the district shall issue a warrant in the amount of said excess to the then holder of title to said tract.
Ca. Water Code § 46380